Read the label of any product you use to ensure the proper amount of material is used. Too much may injure your lawn, too little may cause less than satisfactory results. Each time a lawn is fertilized one pound of nitrogen should be used for every 1,000 square feet.
To calculate how much granular fertilizer you will need to use, look at the fertilizer package. There should be three numbers like 16-16-16, 25-0-2 or something similar. These numbers represent the percentage of Nitrogen, Phosphorus and Potassium contained in the product. The first number represents the percentage of nitrogen in a pound of the fertilizer blend. Since you want 1 pound of actual Nitrogen, divide the first number by 100 which will give you the number of pounds product you will put down per 1,000 square feet of grass. (e.g. 16 / 100 = 6.25 lbs. or 25 / 100 = 4 lbs.).
How often should you fertilize? We recommend treating your lawn every five to eight weeks to maintain a healthy, green lawn. Your first treatment should be done in March or April and your last treatment should be performed mid-October to November for early spring green-up.